1618-1651

Dutch astronomer who discovered Mira Ceti's variability (1638), thus helping undermine the Aristotelian concept of the heavens' immutability. In 1596 David Fabricus noticed a third-magnitude star that faded and disappeared. Holwerda later observed a star—now called Mira Ceti—in the same place and watched as its magnitude fluctuated over 11 months. A professor of logic and astronomy at Franeker's Frisian University, Holwerda later, in Philosophia naturalis seu physica vetus-nova (1651), defended an Aristotelian atomism derived from Pierre Gassendi.